title: The cohort of long-term survivors at the German childhood cancer registry.
abstract: BACKGROUND
  With the increasing number of long-term survivors among patients diagnosed with cancer during childhood, questions concerning late effects have become a major research topic. To ascertain late effects, it is necessary to contact former patients. An essential requirement for such studies is a long-term surveillance (LTS) of former childhood cancer patients in their adolescence and their adulthood. The paper describes the role of the German Childhood Cancer Registry (GCCR) in LTS. A cohort of long-term survivors has been built up over the years. The characteristics of this LTS cohort and strategies for further improvement of LTS will be presented.
  
  
  METHODS
  Since 1980 the GCCR systematically ascertains all malignant neoplasms and benign brain tumours in children under the age of 15 years at diagnosis. Participants are followed up actively by the treating hospitals and the clinical study groups in the first years after diagnosis, and by the GCCR thereafter. Late effects are accessed within the Scientific Society for Paediatric Oncology and Haematology (GPOH) of different groups with different focal points. Those groups are the GCCR (secondary malignant neoplasms), LESS (late effects after chemotherapy), RiSK (late effects after radiotherapy), and the working group on quality of life (quality of life and data on life circumstances). Additionally, the GCCR provides logistics for contacting patients during LTS. The LTS is supported by a recent basic publication ("position paper") by the GPOH. Newly diseased cancer cases are reported to the GCCR very completely. The GCCR contains mainly epidemiological data. Accessorily, the GCCR ascertains a minimum of data for each patient which enables population-based studies involving long-term survivors of childhood cancer.
  
  
  RESULTS
  Out of 37 291 children diagnosed with cancer between 1980 and 2004, 8 896 died (until spring 2007). From those not deceased, 21 987 (77.4%) can be followed up further (i.e. current address is known). For about 70% of the patients in the LTS cohort, follow-up data are available and not older than 5 years. Our experience shows that about 80% of former childhood cancer patients agree to continued data storage at the GCCR, 4% explicitly refuse their consent, the remaining do not answer. LTS for patients with leukemia and lymphomas is particularly complete, whereas for patients with brain tumours it is less complete.
  
  
  CONCLUSIONS
  The LTS is considered highly relevant concerning aspects of clinical quality assurance and epidemiological research. The GCCR can guarantee a continuing development and improvement of existing procedures for LTS. The GCCR expects to achieve contacting a high percentage of former childhood cancer patients also in future LTS, even after long periods of time.
authors.affiliation: German Childhood Cancer Registry (GCCR) at the Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI), University of Mainz, Germany. debling@imbei.uni-mainz.de
authors.forename: D
authors.initials: D
authors.lastname: Debling
authors.forename: C
authors.initials: C
authors.lastname: Spix
authors.forename: M
authors.initials: M
authors.lastname: Blettner
authors.forename: J
authors.initials: J
authors.lastname: Michaelis
authors.forename: P
authors.initials: P
authors.lastname: Kaatsch
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000401:mortality / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005500:Follow-Up Studies; D006801:Humans; D007938:Leukemia / Q000401:mortality / Q000628:therapy*; D008223:Lymphoma / Q000401:mortality / Q000628:therapy*; D009369:Neoplasms / Q000401:mortality / Q000628:therapy*; D016609:Neoplasms, Second Primary / Q000401:mortality / Q000628:therapy; D012042:Registries; D017741:Survivors; D055815:Young Adult